The effects of salt ions on the dynamics and thermodynamics of lysozyme unfolding

Classical molecular dynamics (MD) simulations coupled with metadynamics (MTD) simulations were used to investigate lysozyme unfolding in physiological 0.154 M NaCl salt concentration as well as in 0.5 and 1 M NaCl salt solutions. It was found that lysozyme unfolding dynamics is strongly dependent on the salt concentration. Moreover, the stable low energy denatured states are also different in different salt concentrations. Salt ion-protein interaction seems to stabilize both the native and denatured states, but their relative stability depends on salt concentration. Our simulation results and complementary experimental measurements demonstrate that salt ion-protein interactions facilitate lysozyme unfolding.